I have had a sugar thermometer in my drawer for about 5 years and never used it.
Today I made vanilla fudge, first time ever, it worked 
and it is so gorgeous. I am so proud
So I used this recipe here which was linked to from some other MN thread a couple of weeks ago. It cost quite a bit to make, with the vanilla pod and pint of double cream here comes gallstones and I started to panic slightly when it was boiling and bubbling but then it turned into fudge 
Tip - do not do it while making the childrens tea, like I did. Requires concentration.